The present invention relates to a ratchet claw for use with ratchet teeth formed on a rotatable member so as to prevent the same from rotating in one direction, and more particularly, to a ratchet teeth of the type described above adapted to be used in a digital clock.
In a digital clock of the prior art, a ratchet claw is provided so as to cooperate with ratchet teeth formed on the periphery of a timer setting drum so as to arrest the same at the set position and prevent the rotation thereof in one direction. In order to insure positive and resilient engagement of the ratchet claw with one of the ratchet teeth, a spring is provided one end of which is secured to the ratchet claw while the other end is secured to a stationary portion of the frame of the digital clock. Therefore, an external radial force is applied by the spring to the shaft of the timer setting drum so that the frictional wear is enhanced and excessive play is generated between the shaft and the bearing thereof or between the timer setting drum and the stationary shaft rotatably supporting the same thereby deteriorating the proper function of the digital clock. Such a tendency is further enhanced recently as the ratchet teeth are formed from a plastic material so as to reduce the manufacturing cost.
The present invention aims at avoiding the above described disadvantage of the prior art ratchet mechanism.